LET US LEAVE SOME PROBLEMS FOR OUR CHILDREN, OTHERWISE THEY WILL BE SO BORED

Southern California geology has been absolutely revolutionized since California Division of Mines and Geology Bulletin 170, "The Geology of Southern California.", was published in 1954. For example, the volume contains a reasonably good fault map of the region, so what more could we possibly want to know that was not known then? Well clearly we’d like to know when, where, what size, and how frequently earthquakes occurred on the faults. How much and which way has displacement has occurred on each fault? How much of a fault slips at any given time? How deep do faults extend? How do diverse faults relate to one another? How do the Tertiary basins relate to the faulting? Why do the faults exist in the first place? Several southern California geologists with their special expertise caused quantum jumps in our understanding of California’s faults by tackling these and many other questions in the context of the scientific understanding, dogma, and available technology of the time. Tanya Atwater (plate tectonics), John Crowell (strike-slip basin formation), Clarence Allen (seismotectonics), Kerry Sieh (paleoseismology) provided crucial details that extended our understanding of California faults well beyond their mere locations. Indeed, numerous petrologic, geomorphic, sedimentologic, geophysical problems, some of which we delude ourselves by presuming they are solved, were posed by "Geology of southern California" and are still waiting for intrepid people to ask the right questions. At times we babble so confidently about our apparent understanding of California that our students must wonder if anything remains for them to do. Yes, plenty! New questions will always arise and scream for new technology and new talent to solve. I have no doubt that those same students will become "senior geologists" someday, and will congratulate themselves on how many problems they’ve solved, but will still wring their hands and knot their brows over problems, both simple and complex, that they and we "seniors" never got to or imagined.